President Trump on Friday endorsed South Carolina’s lieutenant governor, Pamela Evette, to be the state’s next governor.

His endorsement comes just days after state lawmakers adjourned a special session without voting on a new congressional map that aimed to eliminate South Carolina’s only majority Black district and lock in an entirely Republican delegation. Ms. Evette had been among the most vocal proponents of the redistricting effort, as Republican-led states across the South have raced to redo their maps in response to the Supreme Court’s weakening of the Voting Rights Act.

In a statement on Truth Social, the president said that Ms. Evette had long supported him, and he lauded her as “a good friend, fighter, and WINNER.”

His endorsement in the crowded Republican primary also meant that he was siding with South Carolina’s current governor, Henry McMaster, who is term-limited and has said he wants Ms. Evette to be his successor.

Mr. Trump wrote that he expected Ms. Evette would choose the governor’s son, Henry McMaster Jr., as her lieutenant governor.

“Your walk down that golden escalator is what propelled me into politics,” Ms. Evette said on social media in response. She added: “I am incredibly grateful for your support and will never let you down.”

Six candidates are running for the Republican nomination: Ms. Evette; U.S. Representatives Ralph Norman and Nancy Mace; Alan Wilson, the state’s attorney general; Rom Reddy, a former business executive; and Josh Kimbrell, a state senator.

Both parties are holding their primaries on June 9. Given how many candidates are running — and that early voting began on Tuesday — the Republican contest may still lead to a runoff, which would take place later in June.

Mr. Trump’s endorsement had loomed large over the Republican primary for months, especially as lawmakers wrestled with whether to redraw the state’s congressional map in an effort to improve their chances of holding onto a narrow Republican majority in the U.S. House. That push collapsed in the State Senate this week, despite the pressure from Mr. Trump, because of concerns about new district lines backfiring on the party and about the number of voters who had already submitted their ballots.

Some of the candidates, often with little daylight between them on policy issues, had jockeyed for ways to demonstrate their allegiance to the president. Ms. Evette’s campaign sent out news releases with a photo of her standing next to Mr. Trump as the header; the president is also pictured at the center of her campaign website.

Mr. Wilson’s campaign website has a section headlined “Trump Tough,” with a slide show of photos of him with the president. It also outlines how Mr. Wilson has defended Mr. Trump’s policies and stances.

In a statement on Friday evening, Mr. Wilson doubled down on his support for the president, saying that “no one’s fought harder or risked more for President Trump and his agenda than I have.”

As recently as Friday morning, Ms. Mace was posting on social media to defend her relationship with Mr. Trump and accusing Ms. Evette of misrepresenting her relationship with the president.

“Even she must realize that after her administration royally screwed up the redistricting fight that no one in the White House wants her as Governor,” Ms. Mace wrote on social media. “Absolutely no one.”